Polymyxin B hemoperfusion: a mechanistic perspective

Integrated Endotoxin Adsorption and Antibacterial Properties of Cationic Polyurethane Foams for Wound Healing

Gram-negative bacteria, containing toxic proinflammatory and pyrogenic substances [endotoxin or lipopolysaccharide (LPS)], can lead to infection and associated serious diseases, such as sepsis and septic shock. Development of antimicrobial materials with intrinsically endotoxin adsorption activity can prevent the release of bacterial toxic components while killing bacteria. Herein, a series of imidazolium-type polyurethane (PU) foams with antimicrobial properties were synthesized. The content effects of cationic moieties on the antimicrobial activities against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus as well as the endotoxin adsorption property were investigated. The obtained PU foams show slightly higher efficiency against two Gram-negative strains than for Gram-positive one and high absorbability of LPS. A wound healing test using P. aeruginosa and its isolated LPS-treated mice as the models further demonstrated that imidazolium-type PU foams combine both antibacterial and endotoxin adsorption properties and may have a potential application as an antimicrobial wound dressing in a clinical setting.

Polymyxin B hemoperfusion in endotoxemic septic shock patients without extreme endotoxemia: a post hoc analysis of the EUPHRATES trial

PURPOSE

The EUPHRATES trial examined the impact of polymyxin B hemoperfusion (PMX) on mortality in patients with septic shock and endotoxemia, defined as EAA ≥ 0.60. No difference was found in 28-day all-cause mortality. However, the trial showed that in some patients with septic shock the burden of endotoxin activity was extreme (EAA ≥ 0.9). In a post hoc analysis, we evaluated the impact of PMX use in patients with septic shock and endotoxin activity measured between 0.6-0.89.

METHODS

Post-hoc analysis of the EUPHRATES trial for the 194 patients with EAA ≥ 0.6-0.89 who completed two treatments (PMX or sham). The primary end point was mortality at 28 days adjusted for APACHE II score and baseline mean arterial pressure (MAP). Additional end points included changes in MAP, cumulative vasopressor index (CVI), median EAA reduction, ventilator-free days (VFD), dialysis-free days (DFD) and hospital length of stay. Subpopulations analyzed were site and type of infection and those with norepinephrine dose > 0.1 mcg/kg/min at baseline.

RESULTS

At 28 days, 23 patients of 88 (26.1%) in the PMX group died versus 39 of 106 (36.8%) in the sham group [risk difference 10.7%, OR 0.52, 95% CI (0.27, 0.99), P = 0.047]. When unadjusted for baseline variables, P = 0.11. The 28-day survival time in the PMX group was longer than for the sham group [HR 0.56 (95% CI 0.33, 0.95) P = 0.03]. PMX treatment compared with sham showed greater change in MAP [median (IQR) 8 mmHg (- 0.5, 19.5) vs. 4 mmHg (- 4.0, 11) P = 0.04] and VFD [median (IQR) 20 days (0.5, 23.5) vs. 6 days (0, 20), P = 0.004]. There were no significant differences in other end points. There was a significant difference in mortality in PMX-treated patients with no bacterial growth on culture [PMX, 6/30 (20%) vs. sham, 13/31 (41.9%), P = 0.005]. The median EAA change in the population was - 12.9% (range: increase 49.2%-reduction 86.3%). The mortality in the above median EAA change group was PMX: 6/38 (15.7%) vs. sham 15/49 (30.6%), P = 0.08.

CONCLUSIONS

These hypothesis-generating results, based on an exploratory post hoc analysis of the EUPHRATES trial, suggest measurable responses in patients with septic shock and an EAA ≥ 0.6 to 0.89 on changes in mean arterial pressure, ventilator-free days and mortality.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT01046669. Funding Spectral Medical Incorporated.

Regional citrate-calcium anticoagulation during polymyxin-B hemoperfusion: A case series

Introduction:

So far, only heparin-based anticoagulation has been proposed during polymyxin-B hemoperfusion. However, postsurgical septic patients can be at high risk of bleeding due to either surgical complications or septic coagulation derangement. Consequently, heparin should not represent in some cases the anticoagulation regimen of choice in this type of patients.

Methods and results:

We present a case series of four postsurgical septic patients treated with polymyxin-B hemoperfusion using regional citrate anticoagulation. All the treatments were performed without complications. During each treatment, there were no episodes of filter clotting, no bleeding, and no metabolic complications for any of the patients.

Conclusion:

To our knowledge, this is the second published report on the use of citrate anticoagulation during polymyxin-B hemoperfusion. Our case series continued to show that regional citrate anticoagulation regimen is feasible and safe during polymyxin-B hemoperfusion treatment in postsurgical septic patients.

Modulation by Polymyxin-B Hemoperfusion of Inflammatory Response Related to Severe Peritonitis

Conflicting results have been reported on the influence of Polymyxin-B hemoperfusion treatment on systemic inflammation markers. The aim of the study was to assess in a randomized control trial the influence on plasma cytokine concentrations of Polymyxin-B hemoperfusion in septic shock due to peritonitis. A panel of 10 pro- or anti-inflammatory cytokines was measured in 213 patients with peritonitis-induced septic shock enrolled in the randomized trial ABDOMIX testing the impact of 2 Polymyxin-B hemoperfusion sessions with standard treatment. Gram-negative bacteria were identified in 69% of patients. In the overall population, baseline plasma cytokine concentrations were not different between the two groups. Circulating tumor necrosis factor-α, interleukin (IL)-1β, IL-10, IL-6, and IL-1RA decreased significantly over time in both groups (P <0.0001 for all in controls, and P = 0.0002, 0.003, and <0.0001 in patients treated with Polymyxin-B hemoperfusion). IL-17A decreased significantly in patients treated with Polymyxin B hemoperfusion (P = 0.045) but not in controls. At the end of the second Polymyxin-B hemoperfusion session or at corresponding time in controls, plasma levels of cytokines did not differ between the two groups. Similar results were found in the subgroup of patients with gram-negative peritonitis who completed two Polymyxin-B hemoperfusion sessions. These results do not support a significant influence of Polymyxin-B hemoperfusion on circulating cytokines assessed except for IL-17A which clinical significance remains to be elucidated.

Inflammation and thrombosis: roles of neutrophils, platelets and endothelial cells and their interactions in thrombus formation during sepsis

The inflammatory response and the activation of coagulation are two important responses in a host's defense against infection. These mechanisms do not work independently, but cooperate in a complex and synchronous manner. Recent research has also shed light on the critical role of thrombus formation, which prevents the dissemination of microorganisms. The cellular components of blood vessels, i.e. leukocytes, platelets, erythrocytes, and vascular endothelial cells, play significant roles in the development of thrombi in combination with activation of the coagulation system. In addition to the cellular components, alarmins such as histones and high-mobility group box 1, microparticles and secreted granule proteins are all important for clot formation. In this summary, we review the pathophysiology of sepsis-induced coagulopathy and the role of cellular components and critical factors released from damaged cells. In addition, we review important therapeutic approaches that have been developed, are under investigation and are currently available in certain countries, including antithrombin, recombinant thrombomodulin, anti-Toll-like receptor 4 therapy, anti-damage associated molecular pattern therapy, and hemoadsorption with a polymyxin B-immobilized fiber column.

The role of adjuvant immunomodulatory agents for treatment of severe influenza

A severe inflammatory immune response with hypercytokinemia occurs in patients hospitalized with severe influenza, such as avian influenza A(H5N1), A(H7N9), and seasonal A(H1N1)pdm09 virus infections. The role of immunomodulatory therapy is unclear as there have been limited published data based on randomized controlled trials (RCTs). Passive immunotherapy such as convalescent plasma and hyperimmune globulin have some studies demonstrating benefit when administered as an adjunctive therapy for severe influenza. Triple combination of oseltamivir, clarithromycin, and naproxen for severe influenza has one study supporting its use, and confirmatory studies would be of great interest. Likewise, confirmatory studies of sirolimus without concomitant corticosteroid therapy should be explored as a research priority. Other agents with potential immunomodulating effects, including non-immune intravenous immunoglobulin, N-acetylcysteine, acute use of statins, macrolides, pamidronate, nitazoxanide, chloroquine, antiC5a antibody, interferons, human mesenchymal stromal cells, mycophenolic acid, peroxisome proliferator-activated receptors agonists, non-steroidal anti-inflammatory agents, mesalazine, herbal medicine, and the role of plasmapheresis and hemoperfusion as rescue therapy have supportive preclinical or observational clinical data, and deserve more investigation preferably by RCTs. Systemic corticosteroids administered in high dose may increase the risk of mortality and morbidity in patients with severe influenza and should not be used, while the clinical utility of low dose systemic corticosteroids requires further investigation.

Adjunctive Therapies During Extracorporeal Membrane Oxygenation to Enhance Multiple Organ Support in Critically Ill Children

Since the advent of extracorporeal membrane oxygenation (ECMO) over 40 years ago, there has been increasing interest in the use of the extracorporeal circuit as a platform for providing multiple organ support. In this review, we will examine the evidence for the use of continuous renal replacement therapy, therapeutic plasma exchange, leukopheresis, adsorptive therapies, and extracorporeal liver support in conjunction with ECMO.

Clinical effects of direct hemoperfusion using a polymyxin B-immobilized fiber column in clinically amyopathic dermatomyositis-associated rapidly progressive interstitial pneumonias

Background

Rapidly progressive interstitial pneumonias (RPIPs) associated with clinically amyopathic dermatomyositis (CADM) are highly resistant to therapy and have a poor prognosis. Multimodal therapies, including direct hemoperfusion using a polymyxin B-immobilized fiber column (PMX-DHP), have a protective effect on RPIPs. We evaluated the effects of PMX-DHP on CADM-associated RPIPs.

Methods

We retrospectively enrolled 14 patients with CADM-associated RPIPs and acute respiratory failure treated with PMX-DHP, corticosteroids, and immunosuppressive agents. Clinical manifestations were compared between survivors and non-survivors at 90 days after PMX-DHP.

Results

The survival rate at 90 days after PMX-DHP was 35.7% (5/14). Before PMX-DHP, the survivor group exhibited a significantly higher PaO₂/FiO₂ (P/F) ratio and serum surfactant protein-D (SP-D) levels and significantly lower lactate dehydrogenase (LDH) and ferritin levels than the non-survivor group. Platelet counts were significantly decreased after PMX-DHP therapy in both groups, but remained higher in the survivor group than the non-survivor group over the course of treatment. Anti-melanoma differentiation-associated gene 5 (MDA-5) antibody positive patients demonstrated a poor 90-day survival rate, lower platelet counts and P/F ratio, and higher LDH levels than anti-MDA-5 antibody negative patients.

Conclusions

CADM-associated RPIPs with anti-MDA-5 antibody is associated with a very poor prognosis. A higher P/F ratio and SP-D level, lower LDH and ferritin levels, higher platelet counts, and anti-MDA-5 antibody negativity are important prognostic markers in patients with CADM-associated RPIPs treated with PMX-DHP.

Intestinal fatty acid-binding protein level as a predictor of 28-day mortality and bowel ischemia in patients with septic shock: A preliminary study

PURPOSE

We sought to evaluate the levels of intestinal fatty acid-binding protein (I-FABP), a biomarker of enterocyte injury, as a predictor of 28-day mortality and bowel ischemia in septic shock patients.

MATERIAL AND METHODS

In this preliminary prospective observational study, 57 adult septic shock patients under mechanical ventilation were enrolled. Serum I-FABP levels and prognostic biomarkers were recorded upon intensive care unit (ICU) admission.

RESULTS

The overall 28-day mortality rate of participants was 23% (13/57). Non-survivors displayed significantly higher lactate (p=0.009), I-FABP (p=0.012), and N-terminal pro-B-type natriuretic peptide (p=0.039) levels compared to survivors. Only I-FABP was associated with 28-day mortality (odds ratio, 1.036; 95% confidence interval, 1.003-1.069; p=0.031) in a multiple logistic regression analysis adjusted for the Acute Physiology and Chronic Health Evaluation II score. When divided into low and high I-FABP groups based on the optimum cut-off value of 19.0ng/mL for predicting 28-day mortality, high-I-FABP patients had a significantly higher incidence of non-occlusive mesenteric ischemia (NOMI) (2% [1/43] vs 29% [4/14]; p=0.011).

CONCLUSIONS

I-FABP level at ICU admission can serve as a predictor of 28-day mortality in septic shock patients and is associated with the incidence of NOMI.

Potential survival benefit of polymyxin B hemoperfusion in patients with septic shock: a propensity-matched cohort study

BACKGROUND

The purpose of this study was to investigate whether polymyxin B hemoperfusion (PMX-HP) improves the survival of patients with septic shock.

METHODS

This was a retrospective, multicenter study conducted on patients treated during a 3-year period. We performed propensity-score analyses of the Japan Septic Disseminated Intravascular Coagulation (JSEPTIC DIC) study database. The study included data on 1723 patients with septic shock aged 16 years or older. Furthermore, we divided patients into to PMX-HP- and non-PMX-HP-treated groups. The primary endpoint was all-cause hospital mortality; secondary endpoints included intensive care unit (ICU) mortality and number of ICU-free days (ICUFDs) in the first 28 days.

RESULTS

Of 1,723 eligible patients, 522 had received PMX-HP. Propensity score matching created 262 matched pairs (i.e., 262 patients in each of the non-PMX-HP and PMX-HP groups). The proportion of all-cause hospital mortality was significantly lower in the PMX-HP group than in the non-PMX-HP group (32.8% vs. 41.2%; odds ratio (OR): 0.681; 95% confidence interval (CI): 0.470-0.987; P = 0.042). The number of ICUFD in the first 28 days was significantly higher in the PMX-HP group than in the non-PMX-HP group (18 (0-22) vs. 14 (0-22) days, respectively; P = 0.045). On the other hand, there was no significant difference in ICU mortality between the two groups (21.8% vs. 24.4%; OR: 0.844; CI: 0.548-1.300; P = 0.443).

CONCLUSIONS

Our results strongly suggest that PMX-HP reduces all-cause hospital mortality and length of ICU stay in patients with septic shock.

Efficacy of direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP) in rapidly progressive interstitial pneumonias: results of a historical control study and a review of previous studies

BACKGROUND

Direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP) therapy has been approved for sepsis-associated acute respiratory distress syndrome, but its efficacy for other rapidly progressive interstitial pneumonias (RPIPs) is unclear. The purpose of this study was to examine the efficacy of PMX-DHP therapy for acute respiratory failure in patients with RPIPs, when compared with a historical control receiving conventional treatment without PMX-DHP.

METHODS

This study comprised 77 patients with RPIPs in our institute between January 2002 and December 2015. The initial 36 patients between January 2002 and March 2007 were treated without PMX-DHP (historical control group), and the following 41 patients between April 2007 and December 2015 were treated with PMX-DHP (PMX-DHP group) once daily for two successive days concurrently with corticosteroids and/or immunosuppressive agents. The 90-day mortality and clinical factors were compared between the groups. Cox proportional hazards models were constructed to analyze 90-day mortality and identify predictors.

RESULTS

The 90-day mortality rate was significantly lower in the PMX-DHP group than in the controls (41.5% versus 66.7%, p = 0.019). PMX-DHP therapy was significantly associated with mortality (hazard ratio 0.505; 95% confidence interval, 0.270-0.904; p = 0.032). There were significant differences in the serial changes in the PaO₂/FiO₂ ratio, SOFA score, and blood neutrophil counts from days 0-5 after PMX-DHP between the survivor and non-survivor groups ( p = 0.015, p < 0.001, p = 0.035, respectively). The improved PaO₂/FiO₂ ratio on day 3 significantly correlated with the change in blood neutrophil counts (r_s = -0.431, p = 0.006).

CONCLUSIONS

PMX-DHP therapy may be effective in RPIPs patients accompanied by acute respiratory failure and is expected to reduce mortality rates.

The Roles of Continuous Renal Replacement Therapy in Septic Acute Kidney Injury

Despite hundreds of clinical and basic studies that have led to a better mechanistic understanding of sepsis, the number of cases with sepsis in the United States is still rising. Sepsis is a common cause of acute kidney injury (AKI) and may explain long-term complications and mortality. In the current article, a new therapeutic concept using continuous renal replacement therapy to prevent and manage long-term sequelae in septic AKI is described.

Effects of polymyxin B hemoperfusion on hemodynamics and prognosis in septic shock patients

PURPOSE

We designed this study to examine the clinical effects of polymyxin B hemoperfusion (PMX-HP) in septic shock patients.

MATERIAL AND METHODS

We retrospectively examined the effects of PMX-HP in septic shock patients with intra-abdominal or gram-negative bacterial infection during October 2013-May 2016. A one-to-one matching between the PMX-HP and conventional groups was performed, and 28-day mortality, and change in inotropic score, Sequential Organ Failure Assessment (SOFA) score, and Acute Physiology and Chronic Health Evaluation II (APACHE II) score at 24h in the two groups were compared. In addition, multivariable regression analysis and Cox proportional hazards regression model were applied in all eligible patients.

RESULTS

Sixty-nine patients were eligible, of whom fifty patients were enrolled for matched cohort analysis. In matched cohort analysis, change in inotropic score after 24h (-24.8 [19.7] vs. -6.4 [20.0], p=0.002) differed significantly between the PMX-HP and conventional groups. Multivariable regression analysis revealed that PMX-HP was associated with lower 28-day mortality (odds ratio 0.18, 95% CI 0.04-0.92, p=0.039) and greater improvement in inotropic and APACHE II scores.

CONCLUSIONS

PMX-HP may have potential benefits for hemodynamic and prognostic outcomes in septic shock patients with intra-abdominal or gram-negative bacterial infection.

Effects of endotoxin absorber hemoperfusion on microcirculation in septic pigs

BACKGROUND

Endotoxins contribute to systemic inflammatory response and microcirculatory dysfunctions under conditions of sepsis. Polymyxin B hemoperfusion (PMX-HP) is used to remove circulating endotoxins and improve clinical outcomes. This study aims to investigate the effect of PMX-HP on microcirculation in septic pigs.

MATERIALS AND METHODS

By using a septic pig model, we tested the hypothesis that PMX-HP can correct intestinal microcirculation, tissue oxygenation saturation, and histopathologic alterations. A total of 18 male pigs were divided into three groups: (1) sham; (2) sepsis (fecal peritonitis); and (3) sepsis + PMX-HP groups. A sidestream dark field video microscope was used to record microcirculation throughout the terminal ileal mucosa, colon mucosa, kidney surface, and sublingual area. A superficial tissue oxygenation monitor employing the light reflectance spectroscopy technique was used to measure the tissue oxygen saturation. Hematoxylin and eosin staining was used for histologic examination.

RESULTS

The perfused small vessel density and tissue oxygen saturation of the ileal mucosa at 6 h were higher in the sepsis + PMX-HP group than those in the sepsis group. The fluid amount and norepinephrine infusion rate between the sepsis group and sepsis + PMX-HP groups did not differ significantly. The histologic score for the ileal mucosa was lower in the sepsis + PMX-HP group than that in the sepsis group. Finally, the urine output was higher in the sepsis + PMX-HP group than it was in the sepsis group.

CONCLUSIONS

This study demonstrates that PMX-HP attenuates microcirculatory dysfunction, tissue desaturation, and histopathologic alterations in the ileal mucosa in septic pigs.

Rapidly progressive interstitial lung disease due to anti-MDA-5 antibody-positive clinically amyopathic dermatomyositis complicated with cervical cancer: Successful treatment with direct hemoperfusion using polymyxin B-immobilized fiber column therapy

The anti-melanoma differentiation-associated gene 5 (MDA-5) antibody is a marker of clinically amyopathic dermatomyositis (CADM) and rapidly progressive interstitial lung disease (ILD) with acute respiratory failure. A 35-year-old woman with cervical cancer showed Gottron's papules, severe hypoxemia, and diffuse ground-glass opacities on chest computed tomography. She was diagnosed with rapidly progressive ILD associated with CADM. Her serum was positive for the anti-MDA-5 antibody. Combination therapy with corticosteroids, immunosuppressants, and direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP) improved her respiratory dysfunction. Eventually, surgery for the cancer was performed successfully. This is the first case to demonstrate the efficacy of PMX-DHP for rapidly progressive ILD with anti-MDA-5 antibody-positive CADM and a malignancy.

Polymyxin B-immobilized fiber column direct hemoperfusion and continuous hemodiafiltration in premature neonates with systemic inflammatory response syndrome

BACKGROUND

There have been no previous studies regarding whether combined use of Polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) and continuous hemodiafiltration (CHDF) is helpful in the treatment of preterm infants with systemic inflammatory response syndrome (SIRS) and hypercytokinemia.

METHODS

A retrospective review was carried out of 18 SIRS infants born at gestational week 24-28. Eight with blood interleukin (IL)-6 ≥ 1000 pg/mL were treated actively with 2 h PMX-DHP followed by 2 h PMX-DHP and CHDF. Ten with IL-6 < 500 pg/mL were treated conventionally (with neither PMX-DHP nor CHDF) and served as controls.

RESULTS

Demographic characteristics were similar except for IL-6, arterial-to-alveolar oxygen tension ratio (a/APO₂ ), and number of immature neutrophils between the two groups. Baseline a/APO₂ was significantly lower in infants with than without active treatment (0.44 vs 0.67, respectively, P = 0.002). After 4 h treatment, the IL-6 decreased to < 500 pg/mL in all eight infants, and a/APO₂ improved significantly to 0.62 (P = 0.006). Bronchopulmonary dysplasia occurred in a similar proportion (63%, 5/8 vs 80%, 8/10, respectively), but the number of days on inhaled oxygen (30 vs 47 days, respectively, P = 0.033) and tracheal intubation (36 vs 51 days, respectively, P = 0.040) was significantly lower in infants with than without active treatment. Prevalence of adverse events was similar (13%, 1/8 vs 50%, 5/10 for active vs conventional treatment, respectively).

CONCLUSION

Active treatment with PMX-DHP and CHDF was helpful in the reduction of days on inhaled oxygen and tracheal intubation in preterm SIRS infants with hypercytokinemia. Further prospective randomized studies are warranted.

Treatment of endotoxaemia and septicaemia in the equine patient

Endotoxins, constituents of the cell wall of gram-positive and gram-negative bacteria, regularly result in severe illness and death in horses. In endotoxaemia, these constituents are present in the systemic circulation; in septicaemia, whole microbes invade normally sterile parts of the body. Interaction of these endotoxins with pathogen recognition receptors leads to an inflammatory response that cannot always be sufficiently contained and hence needs direct treatment. Over the last decennia, our understanding of the pathophysiology of endotoxaemia and septicaemia has significantly increased. Based on improved understanding of the interaction between receptors and endotoxins as well as the subsequent downstream signalling pathways, new therapeutic targets have been identified in laboratory animal species and humans. Important species differences in the recognition of endotoxins and pathogens by their receptors as well as the inflammatory response to receptor activation hamper extrapolation of this information to the horse (and other species). Historically, horses with endotoxaemia and septicaemia have been treated mainly symptomatically and supportively. Based on the identified therapeutic targets, this review describes the current knowledge of the treatment for endotoxaemia and septicaemia in the horse with reference to the findings in other animal species and humans.

The effects of direct hemoperfusion using a polymyxin B-immobilized column in a pig model of severe Pseudomonas aeruginosa pneumonia

Background

Hemoperfusion through a column containing polymyxin B-immobilized fiber (PMX-HP) is beneficial in abdominal sepsis. We assessed the effects of PMX-HP in a model of severe Pseudomonas aeruginosa pneumonia.

Methods

Eighteen pigs with severe P. aeruginosa pneumonia were mechanically ventilated for 76 h. Pigs were randomized to receive standard treatment with fluids and vasoactive drugs, or standard treatment with two 3-h PMX-HP sessions. Antibiotics against P. aeruginosa were never administered. We assessed endotoxemia through the endotoxin activity assay (EA). We measured the static lung elastance, ratio of arterial partial pressure per inspiratory fraction of oxygen (PaO₂/FIO₂), mean arterial pressure, cardiac output, systemic vascular resistance and inotropic score. Finally, every 24 h, we assessed complete blood count.

Results

In comparison with the control group, PMX-HP decreased percentage of circulating neutrophils from 47.4 ± 13.8 to 40.8 ± 11.5 % (p = 0.009). In a subgroup of animals with the worst hemodynamic impairment, EA in the control and PMX-HP groups was 0.50 ± 0.29 and 0.29 ± 0.14, respectively (p = 0.018). Additionally, in the control and PMX-HP groups, static lung elastance was 26.9 ± 8.7 and 25.3 ± 7.5 cm H₂O/L (p = 0.558), PaO₂/FIO₂ was 347.3 ± 61.9 and 356.4 ± 84.0 mmHg (p = 0.118), mean arterial pressure was 81.2 ± 10.3 and 81.6 ± 13.1 mmHg (p = 0.960), cardiac output was 3.30 ± 1.11 and 3.28 ± 1.19 L/min (p = 0.535), systemic vascular resistance was 1982.6 ± 608.4 and 2011.8 ± 750.0 dyne/s/cm^–5 (p = 0.939), and inotropic score was 0.25 ± 0.10 and 0.26 ± 0.18 (p = 0.864).

Conclusions

In mechanically ventilated pigs with severe P. aeruginosa pneumonia, PMX-HP does not have any valuable clinical benefit, and studies are warranted to fully evaluate a potential role of PMX-HP in septic shock associated with severe pulmonary infections.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0155-3) contains supplementary material, which is available to authorized users.

Effect of PMX-DHP for sepsis due to ESBL-producing E. coli in an extremely low-birthweight infant

We report a case of early onset sepsis caused by (CTX for cefotaximase and M for Munich)-type extended-spectrum β-lactamase-producing Escherichia coli (ESBL E. coli) in a preterm infant weighing 601 g. He was given meropenem and treated for endotoxin absorption with polymyxin B-immobilized fibers with only 8 mL of priming volume. The patient survived without any short-term neurological or respiratory sequelae. The choice of antibiotics is particularly important in seriously ill neonates with sepsis due to ESBL-producing organisms. Polymyxin B hemoperfusion might be an innovative therapy for severe neonatal sepsis and could improve outcome even in an extremely low-birthweight infant.

Potential Survival Benefit of Polymyxin B Hemoperfusion in Septic Shock Patients on Continuous Renal Replacement Therapy: A Propensity-Matched Analysis

BACKGROUND/AIMS

We assessed the survival benefit of polymyxin B hemoperfusion (PMX) in septic shock patients starting continuous renal replacement therapy (CRRT), who are known to have an increased rate of mortality.

METHODS

Adult patients in the Japanese diagnosis procedure combination database satisfying the following criteria were enrolled: hospitalized in 2007-2012; diagnosed as having sepsis; required noradrenaline and/or dopamine; and started CRRT in intensive care unit. Propensity scores for receiving PMX were created from patient and hospital characteristics.

RESULTS

Of 3,759 eligible patients, 1,068 received PMX. Propensity-score matching produced a matched cohort of 978 pairs. The 28-day mortality was 40.2% (393/978) in the PMX group and 46.8% (458/978) in the control group (p = 0.003). Logistic regression analysis revealed a significant association between the use of PMX and decreased 28-day mortality (adjusted OR 0.75; 95% CI 0.62-0.91).

CONCLUSION

This large retrospective study suggests that septic shock patients starting CRRT may benefit from PMX.

Multidrug-Resistant Gram-Negative Bacterial Infections in the Hospital Setting: Overview, Implications for Clinical Practice, and Emerging Treatment Options

The increasing prevalence of infections due to multidrug-resistant (MDR) gram-negative bacteria constitutes a serious threat to global public health due to the limited treatment options available and the historically slow pace of development of new antimicrobial agents. Infections due to MDR strains are associated with increased morbidity and mortality and prolonged hospitalization, which translates to a significant burden on healthcare systems. In particular, MDR strains of Enterobacteriaceae (especially Klebsiella pneumoniae and Escherichia coli), Pseudomonas aeruginosa, and Acinetobacter baumannii have emerged as particularly serious concerns. In the United States, MDR strains of these organisms have been reported from hospitals throughout the country and are not limited to a small subset of hospitals. Factors that have contributed to the persistence and spread of MDR gram-negative bacteria include the following: overuse of existing antimicrobial agents, which has led to the development of adaptive resistance mechanisms by bacteria; a lack of good antimicrobial stewardship such that use of multiple broad-spectrum agents has helped perpetuate the cycle of increasing resistance; and a lack of good infection control practices. The rising prevalence of infections due to MDR gram-negative bacteria presents a significant dilemma in selecting empiric antimicrobial therapy in seriously ill hospitalized patients. A prudent initial strategy is to initiate treatment with a broad-spectrum regimen pending the availability of microbiological results allowing for targeted or narrowing of therapy. Empiric therapy with newer agents that exhibit good activity against MDR gram-negative bacterial strains such as tigecycline, ceftolozane-tazobactam, ceftazidime-avibactam, and others in the development pipeline offer promising alternatives to existing agents.

Polymyxin B hemoperfusion prevents acute kidney injury in sepsis model

BACKGROUND

Direct hemoperfusion with a polymyxin B-immobilized column (PMX-DHP) adsorbs endotoxin and has been used for the treatment of septic shock. Yet, the mechanisms by which PMX-DHP acts on acute kidney injury are only partially understood.

MATERIALS AND METHODS

Rats were anesthetized, tracheostomized, and placed on mechanical ventilation. The animals were randomized to three groups: a cecal ligation and puncture (CLP) + dummy-DHP group (n = 10), a CLP + PMX-DHP group (n = 10), and a sham group (n = 4). Four hours after CLP, a dummy-DHP or PMX-DHP was performed for 1 h. The heart rate, mean arterial pressure, arterial blood gases, and plasma concentrations of creatinine, lactate, potassium, interleukin (IL)-6, and IL-10 were measured at 0 h and 8 h. Eight hours after CLP, the kidney was harvested, and histopathologic examination was performed. The expressions of cleaved poly (ADP-ribose) polymerase (PARP) and nuclear factor (NF)-κB p65 were examined by immunohistochemistry. A terminal deoxynucleotide transferase dUTP nick-end labeling assay was performed to detect apoptotic nuclei in kidney sections.

RESULTS

PMX-DHP maintained hemodynamics and the acid-base balance and significantly (P < 0.05) decreased the plasma concentrations of lactate, creatinine, potassium, IL-6, and IL-10 compared with dummy-DHP. PMX-DHP significantly (P < 0.001) attenuated the expressions of cleaved PARP and NF-κB p65 in renal tubular cells and renal tubular cell apoptosis compared with dummy-DHP.

CONCLUSIONS

These findings suggest that PMX-DHP may protect against acute kidney injury not only by inhibiting the NF-κB signaling pathway but also by preventing renal tubular cell apoptosis.

Polymyxin B versus colistin: an update

Polymyxin B and colistin (polymyxin E) are polypeptide antibiotics that were developed in the 1940s, but fell into disfavor due to their high toxicity rates. These two antibiotics were previously regarded to be largely equivalent, due to similarities in their chemical structure and spectrum of activity. In recent years, several pertinent differences, especially in terms of potency and disposition, have been revealed between polymyxin B and colistin. These differences are mainly attributed to the fact that polymyxin B is administered parenterally in its active form, while colistin is administered parenterally as an inactive pro-drug, colistimethate. In this review, we summarize the similarities and differences between polymyxin B and colistin. We also discuss the potential clinical implications of these findings, and provide our perspectives on how polymyxins should be employed to preserve their utility in this era of multi-drug resistance.

From the nephrologist's point of view: diversity of causes and clinical features of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome with multiple entities. Although AKI implies renal damage, functional impairment or both, diagnosis is solely based on the functional parameters of serum creatinine and urine output. The latest definition was provided by the Kidney Disease Improving Global Outcomes (KDIGO) working group in 2012. Independent of the underlying disease, and even in the case of full recovery, AKI is associated with an increased morbidity and mortality. Awareness of the patient's individual risk profile and the diversity of causes and clinical features of AKI is pivotal for optimization of prophylaxes, diagnosis and therapy of each form of AKI. A differentiated and individualized approach is required to improve patient mortality, morbidity, long-term kidney function and eventually the quality of life. In this review, we provide an overview of the different clinical settings in which specific forms of AKI may occur and point out possible diagnostic as well as therapeutic approaches. Secifically AKI is discussed in the context of non-kidney organ failure, organ transplantation, sepsis, malignancy and autoimmune disease.

Polymyxin B-immobilized fiber column hemoperfusion mainly helps to constrict peripheral blood vessels in treatment for septic shock

BACKGROUND

Polymyxin B-immobilized fiber column hemoperfusion (PMX) has been reported to be effective for patients with septic shock. It remains unclear, however, how the efficacy of PMX varies according to the characteristics and underlying conditions of the patients treated. The objective of the present study was to clarify the factors that result in clinical efficacy of PMX treatment.

METHODS

We retrospectively investigated 78 consecutive patients with severe sepsis or septic shock who underwent PMX treatment. We reviewed the demographic data, routine biochemistry, microbiological data, infection focus, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, change in mean arterial pressure (MAP), inotropic score, vasopressor dependency index, plasma levels of endotoxin and lactate, PaO2/FIO2 ratio, and survival time. We also divided the patients into two groups for comparison, namely, those whose inotropic scores improved after PMX treatment (improvement group) and those whose inotropic scores did not improve (non-improvement group).

RESULTS

The inotropic score and the vasopressor dependency index significantly decreased from 18.1 to 9.9 (p < 0.05) and from 0.27 to 0.14 (p < 0.05), respectively, after PMX treatment in the overall study population, while no significant change in the PaO2/FIO2 ratio was observed (p = 0.96). The inotropic score at pre-PMX treatment was significantly higher in the improvement group than in the non-improvement group (p < 0.01). The improvement of the PaO2/FIO2 ratio after PMX treatment was significant in the improvement group (p < 0.05).

CONCLUSIONS

The improvement group's inotropic score was higher, because of peripheral blood vessels dilatation and requirement for more catecholamines. Therefore, our study suggests that PMX treatment is particularly useful for improving hemodynamics in septic shock patients with excessively dilated peripheral blood vessels.